Undy gave you good advise. My 69 NASCAR Cobra with the 428 SCJ has high compression and the book says to run nothing less than 105 octane leaded gas in it. The highest rating we can get here, and it is unleaded is 90. So I keep a barrel of 110 leaded racing gas and use that when I drive it which isn't a lot any more. Aluminum heads would help a lot over the iron ones as they get rid of heat faster.
Ron
